This application claims priority to Korean Patent Application No. 10-2006-0032461, filed on Apr. 10, 2006, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in its entirety are herein incorporated by reference.
1. Field of the Invention
The present invention relates to a surface emitting device using a photonic crystal and a method for fabricating the device. More particularly, the present invention relates to a surface emitting device including a two-dimensional slab type photonic crystal structure wherein quantum dots are formed on an inner wall defining air holes and are excited to emit light, and a method for fabricating the surface emitting device.
2. Description of the Related Art
Photonic crystals have a structure in which two materials having different refractive indices or dielectric constants are regularly arranged in a lattice pattern. This regular arrangement enables formation of a photonic bandgap, which acts to prevent a specific set of wavelengths of electromagnetic radiation from propagating into a photonic crystal. In the case where the photonic bandgap of a photonic crystal is in the visible range and the frequency or wavelength of light incident on the photonic crystal corresponds to the photonic bandgap, 99% or more of the incident light is theoretically reflected from the photonic crystal. In contrast, a large portion of light having a frequency or wavelength other than the photonic bandgap of a photonic crystal passes through the photonic crystal. For these reasons, photonic crystals are expected to considerably increase the ability to control of light. Because of such circumstances, photonic crystals are actively being investigated as potential materials for next-generation optical devices.
When light of a particular wavelength is generated in cavities formed within a photonic crystal, it collides with and is continuously reflected from the wall of the cavities, and as a result, the light is confined within the photonic crystal. The light confined within the small cavities is amplified and exits to produce laser light. Further, some waveguides, along which the confined light travels, may be formed within the photonic crystal to produce photonic integrated circuits.
Photonic bandgap structure materials using photonic crystals have been investigated around the world for their potential use in a variety of optoelectronic devices, particularly, microlasers, filters, high-efficiency light-emitting diodes (“LEDs”), optical switches and low-loss waveguides.
For example, U.S. Patent Application Publication No. 2005-111805 discloses an optical fiber comprising a guide region where light is confined, a plurality of holes in the optical fiber, and a plurality of quantum dots in the holes. According to this publication, excitation light for exciting the quantum dots formed within the holes is also confined within the optical fiber and then exits in the same direction as a wave emitted from the quantum dots, thus making surface emission impossible.
Further, Korean Patent Laid-open No. 2000-018855 discloses a photosensitive device using quantum islands wherein the device comprises a first quantum island layer containing quantum dots, a light-absorbing layer including at least one quantum island layer, which is formed by alternately forming materials having a bandgap different from that of the first quantum island layer, a conductive path layer where carriers excited from the light-absorbing layer are collected to cause horizontal conduction, an impurity layer, and two or more detection electrodes for horizontally conducting the carriers, which are excited by receiving light excited from the light-absorbing layer, collected in channels. According to the photosensitive device, the quantum island layer detects light and emits carriers corresponding to the detected light. Accordingly, the photosensitive device can be used as a light-emitting diode, a laser diode, or the like.
The aforementioned prior art publications however fail to disclose a surface emitting device wherein light exits toward the surface of the device. Therefore, there is a need to develop a surface emitting device that can emit light toward the surface of the device and that can control the emission of light that is close to monochromatic light.